Flat Roofers

If you’re looking for flat roofers in the San Francisco Bay Area, consider Airtight Construction. We can help you with your flat roof installation, maintenance and many other roofing services. Our expert team of commercial roofers has decades of experience with flat roofing and other types of commercial roofing. Whether you’re looking for a new flat roof, need advice on roofing systems, need roof repair or maintenance, or want to modify an existing roof, look no further. We have a proven track record of happy customers who can attest to the quality of our flat roof work.


What is a flat roof?

Ironically, flat roofs aren’t actually flat! A fully flat roof would be something of a hazard, allowing no way for dirt and water to roll off. Instead, a proper flat roof installation creates a low slope, usually of between 1/4 to 1/2 inch per foot, ensuring that water can drain effectively.

However, due to the low slope, precipitation may sit on the roof for a much longer time than on a pitched roof. This is one reason why a flat roof needs a considerably different design. On a sloping roof, you have asphalt shingles, or something similar. These overlap like fish scales, staying watertight. Water skims down them, and cannot penetrate.

Flat roofs, on the other hand, are one continuous surface. This means standing water can gather for a time and roofing materials that are resilient to water must be used. The roof also needs to be watertight. In order to create this quality of surface, there are 3 main flat roof systems used for commercial roofing.

Single-ply, or membrane roofing

As a San Francisco roofing company, we see single-ply in many new roof installation choices. While there’s different types of membranes, including plastic and rubber, you’ve likely heard of EPDM the most. Ethylene propylene diene monomer is a synthetic rubber sheet material. Many people know it as a pond liner. It has much of the same effect on your roof!

In this roof style, you have insulation boards over which the layer is laid. Depending on the type of membrane and the advice of the roofing contractor, these could be air welded, loose-laid with ballast such as stone, fastened, or firmly glued.

Single-ply, or membrane roofing

Pros of single-ply flat roofing

With this style of flat roofing, repairs are simple and easy. As many commercial buildings are rather large, this makes your life- and that of your local roofers- considerably easier! Here are some other pros:

  • Leaks are rare if the sheet is well kept
  • The roof deck doesn’t need to be braced, and it’s a light roof overall, yet still durable
  • Membranes are an energy-efficient choice, reflecting heat and UV rays and insulating the building.

Cons of a membrane roof system

The largest con of this flat roof is related to its biggest pro! The more you have on your roof- for example, chimneys, HVAC access, skylights, and pipes- the more complicated ensuring a smooth, flat membrane surface on the roof is. You need an experienced roofing contractor to ensure each penetration is leak proofed correctly. Other considerations are:

  • Seams need to be correctly laid to ensure they, too, don’t leak, or they will need repairing
  • The membrane must be monitored for punctures. This can be caused by poor installation or storm damages.

As a San Francisco Bay Area roofing contractor, we find that a single-ply membrane roofs are quite popular for businesses and various types of commercial buildings. They provide an efficient roof system that works very well. However, it’s a newer technology, and your existing roof may not be using a membrane roof system. Roof replacement can be costly on a large structure, so we try to work with the client’s existing flat roofing where possible.

MBR Roofing

Modified bitumen roofing (MBR) dates form the 1960s. It was the first step to addressing the weight issue of BUR. It’s flexible, and bears some resemblance to residential pitched roofs. This has a mineral ‘top coat’ added, again like a residential roof.

It is rolled out in sheets, with the standard size being 3 foot wide. It uses a base membrane, but this isn’t the same as is used in ‘single-ply’ roofing. While it doesn’t smell or make a mess, it does need heating to install. It is melted to the base layer, effectively. Today you will also find ‘peel and stick’ sheets, but it’s not quite as effective.


MBR roofing advantages

While this type of roofing doesn’t get as much attention as other types of flat roofing, it does have some things going for it. The installation is more consistent than other types of flat roof, because the mineral surface is applied at the factory. It’s relatively simple to install, although not as easy as a single-ply roof. Of course, using a professional roofing company in the Bay Area means you don’t have to worry about that. Other advantages?

  • Maintenance needs are low, and it holds up well
  • The materials are flexible and elastic in the cold, although single-ply is better
  • Represents a good midpoint in flat roofs between the other 2 styles

What are the disadvantages of MBR flat roofs?

Before you decide on MBR roof replacement, what should you know about this type of roofing?

  • As with a single-ply flat roof, joints must be installed professionally or they will leak. Repair for flat roofs like this is tricky and there may be safety concerns.
  • It’s hard to undertake roof repair or roofing work on after installation, for that same reason
  • Open flames are used in the installation, unlike the safer hot air of EPDM
  • It’s not as attractive to the eye as some other roofing.

Deciding on a flat roof installation or repair

Now you know a little more about the types of commercial flat roofs here in the San Francisco Bay Area, it’s time to ask the key question. Do you need roof repair, or is it time for a whole new roof to be installed? Roofs have a finite lifespan, even when they’re well-installed and high-quality. Reroofing may seem intimidating, but sometimes it’s the best way to go, especially if you encounter issues like mold or durability problems.

Obviously, the costs associated with roofing repairs are typically lower than the investment for new roofing, but sometimes it’s not practical anymore to continue to repair. Over time, too many repairs can damage the roofing, lowering the quality of the original project and causing more roofing issues than it solves. Roof replacement may be the best choice.

A professional roofing company like ATC can assess the state of your roof and help you to decide how to best proceed. The Airtight Construction team has been working in the San Francisco Bay Area for decades now, delivering quality roofing installations as well as assisting customers with maintenance plans and repairs to commercial roofs.

In need of commercial flat roof services in the Bay Area? Why not contact the Airtight Construction team today to discuss your specific project needs, or to request a quote.